Ethan Siegel

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.


The Physics of the Death Star

How to destroy an Alderaan-sized planet.

“What’s that star?
It’s the Death Star.
What does it do?
It does Death. It does Death

Mostly Mute Monday: The Largest Eruption In The Known Universe

A galaxy cluster that’s been actively devouring matter for hundreds of millions of years blows all the records away.


Weekend Diversion: The Logic That Stumped Brooklyn Nine Nine

The most famous logic puzzle from the best police comedy on television, and how to (finally) solve it!


Ask Ethan #89: The Universe’s Dark Ages

After the CMB, before the first stars, there was nothing to see. Or was there?

“[I]f there were no light in the universe…

Publications edited by Ethan Siegel

The Universe is out there, waiting for you to discover it.


Throwback Thursday: Are asteroids dangerous?

Sure, they wiped out the dinosaurs, but do they really pose a risk to humans?

“The oldest and strongest emotion of

The Invisible Mountains of Earth

How gravity teaches us that the mountains we see extend far underground.

“Journalists often ask me when I go to the field, ‘What

What’s causing Ceres’ white spots?

A series of mysterious white features lurk at the bottom of one of its most massive craters. Here’s what they could be, and how we’ll find out!


Mostly Mute Monday: Terrific Tails, For A Time

The unique sight of a comet only scratches the surface of an amazing story.

“Without any doubt, the regularity which

Weekend Diversion: Raw Ingredients, Cubed

How food, art, and design come together to display a beauty rarely seen.

“That’s what you get for being food.” -Margaret…

Ask Ethan #88: Where is the Cosmic Microwave Background?

It’s the oldest, most distant light we’ve ever seen. But where, exactly, is it?

“We are told to let our

Throwback Thursday: Stop Sexism in Science

Whether or not you believe there’s a problem, we’re all part of the solution.